I have been to the "fax your MP" Website and faxed.My M P is the magnificently "off-message" Bob Marshall-Andrews QC.
I have also emailed my fax to about 25 folk acquaintances for re-use - and also to Colin Green at the DCMS who I happen to know a bit.
Don't forget the threat is bigger than just to music in pubs. It's to dance and music everywhere in England - licensed premises, unlicensed ones, your house, and the streets and fields. See my post to the "Change music" thread.